1. Field of the Invention
The present invention relates generally to foldable support means for supporting a table machine, and more particularly, to a folding mechanism for supporting a table machine, which can effectively convert the weight of the table machine that is supported on the folding mechanism into a force necessary for folding the folding mechanism.
2. Description of the Related Art
Referring to FIGS. 1-3, a conventional mobile stand 2 for supporting a table machine, for example, table saw 1 is shown in these drawings. The mobile stand 2 comprises a platform 3 for carrying the table saw 1, a pair of first legs 4 each having one end respectively pivoted to the platform 3 by a pin 2a and connected to a handle 4a and the other end terminating in a bearing portion 4b for touching the floor, a pair of second legs 5 each having one end respectively and pivotally connected to the first legs 4 by a pin 2b and terminating in an extension 5b and the other end mounted with a wheel 5a, and a pair of connecting members 6 each having the two distal ends respectively pivoted to the platform 3 and the extension 5b of the second legs 5 by pins 2c and 2d. By means of the aforesaid arrangement, the mobile stand 2 can be alternately set between an extended position shown in FIG. 1 and a received position shown in FIG. 3.
The design of the aforesaid mobile stand 2 allows utilization of the weight of the table saw 1 to share the force F1 necessary for folding the mobile stand 2 into the received position. However, when the bearing portions 4b of the first legs 4 are stopped at the floor, the table saw 1 is kept in a tilted position, and the center of gravity W of the table saw 1 is offset from the pivot points, i.e. pins 2b, between the first legs 4 and the second legs 5 (see FIG. 2), if the grasp force F2 applied by the user to the handle 4a cannot sustain the downward pressure of the table saw 1, the second legs 5 will be forced to move toward the first legs 4 rapidly, and the elastic force of the springs 7 between the first legs 4 and the second legs 5 will accelerate the movement of the second legs 5 toward the first legs 4, resulting in a potential accident.
Further, when the mobile stand 2 is extended out, the shank 8a of each T-shaped lock member 8 is respectively inserted through a through hole 4c on each first leg 4 and a through hole 9a on a respective locating plate 9 that is respectively welded to each of the second legs 5 to lock the first legs 4 and the second legs 5, preventing movement of the second legs 5 toward the first legs 4. When the mobile stand 2 is in the received position, the shanks 8a of the T-shaped lock members 8 are respectively stopped at the extensions 5b of the second legs 5, preventing movement of the second legs 5 relative to the first legs 4. The T-shaped lock members 8 provide a locking and positioning function. However, it is difficult to align the through holes 4c of the first legs 4 with the through holes 9a on the locating plates 9 at the second legs 5. Further, the T-shaped lock members 8 must be pulled out of the locking position or pushed into the locking position when the mobile stand 2 is extended out or received. Further, a shearing force may be produced between the first legs 4 and the second legs 5 due to an accidental impact of the mobile stand 2, thereby damaging the T-shaped lock members 8.
Therefore, the aforesaid conventional mobile stand having the above-mentioned drawbacks is needed to be further improved.